Seismic source for use while submerged in a liquid medium

ABSTRACT

Seismic source for use in an aqueous medium utilizes an elastomer member supported by and disposed on at least a portion of a supporting structure. The supporting structure preferably includes a number of tubular members connected at the trailing end to a bell-shaped member and at a towing end to a pair of bell-shaped members positioned to discharge liquid from the medium into the tubular members. An explosively combustible fluid is introduced into the chamber formed by the elastomer member and the support structure through a mixing chamber and an elongated pipe that extends into the chamber. The explosive fluid is ignited in the mixing chamber. Pump means is provided for removing liquid from the interior of the chamber.

United States Patent 11/1969 Barry et al. 18l/O.5

Primary Examiner- Rodney D. Bennett, Jr.

Assistant ExaminerDaniel C. Kaufman Att0rneys-James A. Reilly, John B.Davidson, Lewis H.

Eatherton and James E. Reed ABSTRACT: Seismic source for use in anaqueous medium utilizes an elastomer member supported by and disposed onat least a portion of a supporting structure. The supporting structurepreferably includes a number of tubular members connected at thetrailing end to a bell-shaped member and at a towing end to a pair ofbell-shaped members positioned to discharge liquid from the'medium intothe tubular members.

An explosively combustible fluid is introduced into the chamber formedby the elastomer member and the support structure through a mixingchamber and an elongated pipe that extends into the chamber. Theexplosive fluid is ignited in the mixing chamber. Pump means is providedfor removing liquid from the interior of the chamber.

[72] lnventor EdR.McCarter 3,480,101

Houston, Tex. [21] AppLNo. 742,387 [22] Filed July3, 1968 [45] PatentedFeb. 16,1971 [73] Assignee Esso Production Research Company acorporation of Delaware [54] SEISMIC SOURCE FOR USE WHILE SUBMERGED IN ALIQUID MEDIUM 9 Claims, 7 Drawing Figs.

[52] U.S.Cl 181/05 51 l nt Cl. 601v 1/04 [50] FieldofSearch..181/0.5(IC) 5 6] References Cited UNITED STATES PATENTS 2,994,3978/1961 Huckabay 181/05 3,330,551 4/1968 Lang 18l/0.5

SPACER &3? MEMBERS 1 29 as 33 OXYGEN? 3 212m 25 3| 23A S 7\5 2s 2'7SOLENOID VALVE Patented Feb. 16, 1971 2 Sheets-Sheet 2 ED R MCCARTERINVENTOR.

1 m MM ATTORNEY SEISMIC SOURCE FOR USE WHILE SUBMERGED IN A LIQUIDMEDIUM BACKGROUND OF THE INVENTION This invention is directed to seismicsources for use at marine locations and more particularly to seismicsources using an explosive gaseous mixture in an enclosure that includesa flexible, expansible elastomer.

Various types of nondynamite seismic wave sources have been developed inrecent years for use at marine locations. One of the most successful ofthese sources uses a supporting structure to which is affixedan'expansible elastomer member to form a combustion chamber forexplosive gases. Means are provided connected to the supportingstructure for introducing an explosive fluid into the combustionchamber, and for igniting the fluid. Also provided is means forexhausting spent gases from the enclosure after production of theseismic pulse. Preferably the supporting structure includes a pluralityof tubular members, and bell-shaped members at each end of the tubularmembers for holding the tubular members in predetermined spatialrelationship, such that a coolant (preferably the liquid within whichthe apparatus is submerged) may flow therethrough to cool the supportingstructure and the gases within the enclosure formed by the supportingstructure and the elastomer member. This seismic wave source has metwith wide commercial acceptance and is used at many locations throughoutthe world in routine seismic exploration operations.

While the apparatus described immediately above has been outstandinglysuccessful as a seismic source, in operation it has been found to sufferfrom certain shortcomings. For example, water has been found to build upwithin the expansible enclosure which can interfere with detonation ofthe explosive fluid therewithin. Furthermore, as compared to dynamite itis not an exceptionally strong source so that any improvement in thestrength of the seismic waves produced thereby can be quite adantageous.

SUMMARY OF THE INVENTION In accordance with one aspect of the inventiona seismic wave source for use at marine locations is provided by meansof a support structure, an expansible elastomer member supported by anddisposed on at least a portion of the supporting structure to define anexpansible chamber therewith, and means for discharging gases to theatmosphere. There is also provided means including an elongated conduitextending into the structure for introducing explosive material into thechamber along with means for detonating the explosive material so as toproduce a high-velocity explosion wavefront down the elongated conduitinto the expansible chamber. In accordance with another aspect of theinvention, there is provided a pump for removing liquid condensate fromthe enclosure. Preferably the pump is a venturi pump actuated by a lineextending to a remote location for conducting a high-pressure liquidstream to the pump.

Objects and features of the invention not apparent from the abovediscussion will become evident upon consideration of the followingdetailed description of the invention taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side view, partially in section, of a seismic energy sourcein accordance with the teachings of the invention.

FIG. 2 is a cross-sectional view of the venturi pump illustrated in FIG.1.

FIG. 3 is a schematic diagram of control apparatus and gas sources forsupplying an explosive gaseous mixture to the apparatus of FIG. 1.

FIG. 4 is an electrical schematic diagram of apparatus for controllingthe detonation of explosive gases introduced into the apparatus of FIG.1 and for controlling the operation of certain component parts of theapparatus of FIG. 1.

s DETAILED DESCRIPTION OF THE INVENTION With reference now generally toFIGS. 1, 2, 5, and 6, there is shown a sound source for use at marinelocations in ac cordance with the present invention. The apparatus usesan expansible, inflatable, elastomeric member 33 which preferably is inthe shape of a cylindrical sleeve elastomer when there is nodifferential pressure thereacross. In FIGS. 1 and 5 the member isillustrated in one of the many shapes that the elastomer sleeve 33 couldassume when a vacuum is drawing the elastomer sleeve member 33 inwardly,as will be described below. The elastomer sleeve member 33 is affixed toa supporting structure including end members 29 and 43 which preferablyare bell-shaped and are connected together by a plurality of tubularmembers 37 which, as illustrated in FIG. 5, are arranged on a closedcurvilinear path, preferably a circular path. The end bell members 29and 43 extend outwardly from the tubular members 37 and away from eachother. The elastomer sleeve member 33 is affixed to the bell member 29by bands 35, and to the bell member 43 by bands 47. Disposed within thebell member 29 and substantially concentric therewith is a thirdbell-shaped member 31 which also is affixed to the tubular members 37.The spaces between the tubular members 37 and the bell-shaped members 29and 31 are plugged so that water flowing between the bell-shaped members29 and 31 will discharge only into the tubular members 37. Asillustrated, the tubular members 37 are open at both ends thereof sothat water can flow freely therethrough. A plurality of spacer members30 at the ends of the bellshaped members 29 and 31 opposite the tubularmembers 37 are for the purpose of maintaining the tubular members spacedapart but permitting free flow of water therethrough. The paralleltubular members 37 are illustrated as being 12 in number and, asmentioned above, as being arranged in predetermined spatialrelationship, preferably parallel and in a circular pattern. The tubularmembers are held in such parallel spaced relationship by annular spiders39 which are brazed or welded thereto. Each of the spiders has a centralopening therein so that gases may pass freely through the chamber. Thetubular members are also held in spaced relationship by closed endmember 41 which also serves to confine the gases within the combustionchamber. In other words, member 41 prevents gases from escaping out theend of the assembly. The member 41 is affixed to the end bell 43. Theend of the bell member 31 opposite the tubular member 37 is closed by asupport plate 26 which also serves to support a combustion chamberassembly 25, and an exhaust conduit 9.

Details of construction of the mixing chamber 25 are shown in FIG. 6.Lines 3 and 5, respectively, lead to a source of ox ygen and to a sourceof a combustible gas, such as propane or acetylene, aboard a ship at aremote location. The lines are connected to the mixing chamber 25 bysolenoid actuated valves 21 and 23 respectively and by pipe sections 21Aand 23A respectively. Gases injected into the chamber through lines 21Aand 23A are mixed therein and are passed into the chamber formed by thesupport structure and elastomer member, as described above, through anelongated pipe 27 which is connected through the plate 26. In theimmediate vicinity of the opening of the pipe 27 into the mixingchamber. there is provided an electrically actuated combustioninitiating means 8, preferably a spark plug 8 having a pair ofelectrodes 10 which are electrically energized from an electrical sourceaboard ship, as will be described below. The elongated pipe 27 extendsfrom the plate 26 through the bell member 31 and through the spacebetween the tubular members 37 to a point near the plate 41. As shownmost perspicuously in FIG.

5, a plurality of spacer members 2 support the pipe within one of thespider rings 39. It is not absolutely necessary that'the pipe 27 extendas far as shown in the drawing. The function of the pipe is primarily toproduce a high-velocity combustion front that will eject into thechamber formed by the supporting structure and the elastomer member toproduce a sudden, powerful detonation of the explosive gases in thechamber. The length-to-diameter ratio of the pipe should be between 75and 300 so that the combustion front is propagated down the pipe at ashigh a velocity as possible and so that the energy of the seismic pulseproduced by the release of the chemical energy of the explosive gaswithin the chamber is maximized. When the ratio is below 75, it has beenfound that the velocity of the front is slowed to an undesirable extent.When a ratio above 300 is used, the velocity of the combustion frontdoes not increase appreciably.

The exhaust conduit 9 opens into the interior of bell member 31 throughplate 26 and extends to the water surface for the purpose of exhaustingproducts of combustion from the combustion chamber. A check valve (notshown) is included within the conduit 9. The check valve may be a ballcheck valve having a relatively heavy movable ball closure member thatis normally spring-biased into engagement with a ball seat. The checkvalve normally prevents fluid passage into the bell member 31 from theconduit 9 and permits products of combustion to exhaust the interior ofthe bell-shaped member 31 only after the ball is unseated. The reasonfor making the ball member relatively heavy, preferably at least 3 to 5pounds, is to provide sufficient inertia that the pressure within thecombustion chamber can build up past the pressure normally required tounseat the ball member from its seat, before the check valve actually isopened. This phenomenon is described in some detail in US. Pat.3,480,101.

Within the bell-shaped member 43 there is disposed a venturi pump 51which may be affixed to the interior of the bellshaped member 43 bysuitable struts (not shown). As illustrated most perspicuously in FIG.2, the venturi pump comprises a pipe member 1 having a nipple 57 at itsend. The bore 1A of the pipe member 1 narrows to a very small diameterat its end 61. The nipple 57 is disposed within a chamber formed bymember 51. A tail pipe section 59 receives high-pressure fluid from theline 1 and the nipple end 61. The liquid is discharged into the chamberof the bell member 43. The housing member 51 is connected to thecombustion chamber through pipe section 54, ball check valve section 52,strainer section 56, and a flexible conduit 58 which is threaded into anopening in the end bell 43 which extends through the bell to within thecombustion chamber. This opening 62 opens into the combustion chamber inthe natural sump formed by the elastomer member and by the end bell atthe trailing end of the end bell. The line 1 for high-pressure liquidextends through one of the conduit members 37 through the space betweenthe end bell-shaped members 29 and 31 to a pressurized liquid source(not shown) aboard ship. Pressurized liquid passing through the line 1will be ejected through the narrow opening at the end of the nipple 57and out the pipe section 59 into the water medium within which the soundsource is disposed. Inasmuch as molecules of the fluid around the nipple57 will be dragged out of chamber 51A by the rapidly moving liquidstream, a vacuum will tend to be produced within the chamber 51A. Thiswill unseat the valve 52A of check valve 52 from its seat 52B so thatliquid will be sucked from within the combustion chamber, throughconduit 58 and strainer 53, check valve 52, and the chamber 51A and outthe end of pipe member 59. The strainer 56 of member 53 may becommercially available steel wool,

. Preferably a fairing is provided to protect the various conduits l, 3,5, 7, and 9, and the associated valving illustrated in FIG. 1 for ashort distaNce from the plate 26. A suitable fairing is illustrated inthe above referenced patent application of A. Barry et al.

.11'1 H0. 3 there is illustrated suitable apparatus for controlling theinjection of gases into the mixing manifold 25. As

indicated above, a source 67 of oxygen or oxygen-enriched air isconnected to pipe section 21A through solenoid actuated valve member 21,which may be a device such as Model V5, manufactured by Skinner ElectricValve Company, New Britain, Connecticut. Likewise, a combustible gassource 69 is connected through line 5 and a solenoid actuated valvemember 23 to line 23A. It is desirable that the solenoid valves beactuated simultaneously for a very precisely controlled time so that adesired quantity of gas can be injected into the apparatus previouslydescribed with regard to FIG. 1. To this end the electrical leads 77A ofsolenoid of valve 21 and the leads 77B of solenoid of valve 23 areconnected in parallel and to a source of electrical energy 75 which maybe aboard ship through a pushbutton switch 73 and an electrical timer71. The timer 71 may be of the type manufactured by Cramer ControlsCorporation of Old Saybrook, Connecticut, Model 412. Upon closure ofnormally open pushbutton switch 73 the timer 71 connects the battery orenergy source 75 to the lines 77A and 778 for the purpose of actuatingthe solenoids of the valve members 21 and 23 to open simultaneously thevalves for a brief period of time, typically 1 to 3 seconds ascontrolled by the timer 71. It has been found satisfactory when using asource having a sleeve 33 that is about'l20 cm long and 25 cm indiameter when no differentialpressure thereacross, to inject therein atotal of between 40000 cc to 12,000 cc of gas- (measured at standardtemperature and pressure).

When it is desired to produce a seismic impulse of maximum power, thetimer 71 may be short-circuited and gas injected into the chamber untilthe check valve within conduit 9 opens.

With reference now to FIG. 4 there is illustrated an electricalschematic diagram of suitable apparatus for actuating the spark plug 8in timed relationship with the actuation of solenoid valve 15. Thesecondary of an ignition coil or transformer 99 is connected toelectrical terminals 101 to which electrical leads to the electrodes ofthe spark plug may be connected. The primary of transformer 99 is'connected in series circuit relationship with a resistor 97 andcapacitor 95 across the terminals ofa high-voltage power source 82 whichis aboard ship. A silicon controlled rectifier 85 and a diode 91 areconnected in parallel with capacitor and the primary of ignitiontransformer 99 so that, when the silicon controlled rectifier 85 isbiased to conduction the capacitor 95 will discharge through the siliconcontrolled rectifier 85, the diode 91, and the primary of the ignitiontransformer 99. The control electrode 88 of the silicon controlledrectifier 85 isconnected to a resistor 93 which is connected to theanode of the diode 91. A voltage source 81 is connected in parallel withthe resistor 93 by means of a normally open pushbutton switch 83.Alternative- 1y, switch 83 may be the conventional switch on a seismicrecorder which controls the initiation of a seismic impulse. The valueof resistor 93 is such that leakage current therethrough will normallybias the silicon controlled rectifier to substantial nonconduction. Whenswitch 83 is closed, battery 81 will bias the silicon controlledrectifier to conduction to discharge capacitor 95 through the primary ofignition transformer 99, thus producing a spark across the terminals ofthe spark plug 8. Between closures of switch 83, high-voltage powersource 82 will recharge the capacitor 95 through the resistor 97 andprimary of ignition transformer 99.

The overall operation of the apparatus described above will now bestated. lnitially timers 71 and 103 are set to provide the desiredquantity of gas to enter the combustion chamber before initiation of aseismic pulse. High-pressure liquid, which may be from the water withinwhich the source is submerged, is injected into line 1 so that a partialvacuum is induced within the interior of and then combustion proceedSwitch 73 is closed to open the solenoid the combustion 21 and 23 toinject a predetermined amount of combustible mixture into the apparatusdescribed above. The gas will enter into the mixing manifold 25 and willpass through the elongated tubular member 27 into the combustion chamberdefined by bell members 29, 31, and 43, end plate 26, plate 41, and theelastomer sleeve member 33. Upon closure of switch 83 a spark will beproduced across the electrodes to ignite the combustible fluids withinthe manifold 25. A high velocity combustion front will be propagateddown tube 27 and will eject into the far end of the chamber and thenwill proceed back through the chamber towards plate 26. When thecombustion front ejects into the chamber, the combustion of the gases inthe chamber is extremely rapid, so that the chemical energy therein isreleased over a very short time interval. As the pressure within thecombustion chamber increases, the elastomer will inflate and expand toproduce a seismic pulse. When the pressure in the combustion chamber issufficient to unseat the ball member within the conduit 9, the valvewill not immediately open but because of the inertia of the ball memberthis will permit maximum expansion of the elastomer member. Whenthe'valve'within the conduit does open, the gases within the combustionchamber will quickly rush out. Meanwhile, as the apparatus is beingtowed through the water, the gases within the combustion chamber will becooled to enhance the partial vacuum thus produced. Inevitably, therewill be some condensation of the combustion products remaining withinthe combustion chamber. The venturi pump described above will produce avacuum somewhat lower than that within the combustion chamber so thatsuch liquid products of combustion will be sucked out of the combustionchamber and into the water around the seismic source. Should the venturipump fail to operate or should it not produce a sufficiently low vacuum,ball 52A will seat on seat 528 to prevent water from backflowing intothe combustion chamber. The steel wool in filter 53 will prevent anysolid matter from preventing seating of the ball valve 52A. It has beenfound that the inclusion of the elongated pipe 27 in the seismic sourcedescribed above produces an increase in seismic wave energy of 50 to 100percent over the energy of the seismic waves produced without theelongated pipe 27 as a result of more complete and effective combustionof the gases over a shorter period of time. This relationship prevailsuntil just before there has been pumped into the apparatus the absolutemaximum amount of gas that the apparatus can accept prior to opening ofthe valve in the exhaust conduit. Thus, the inclusion of the pipe 27makes it possible to produce seismic waves having almost the maximumamount of energy that the apparatus is capable of producing while usingmuch less than the absolute maximum amount of gas that the apparatus canaccept. The maximum amplitude of the output signals from pressureqypedetectors positioned 14 feet away from the seismic source has been foundto be increased as much as 250 percent by the inclusion of pipe 27 as aresult of the increase in the amplitude of seismic energy, as describedabove.

While there has been shown and described what at present is consideredto be the preferred embodiment of the present invention, othermodifications will be apparent to those skilled in the art which do notdepart from the scope of the broadest aspects of the invention.

lclaim:

l. A seismic wave energy source for use while submerged in a liquidmedium comprising:

a supporting structure, an expansible elastic member supported by anddisposed upon at least a portion of the supporting structure to definean expansible chamber therewith, means for discharging gases from saidstructure, first means comprising an elongated conduit extending intosaid supporting structure for introducing explosive fluid through theconduit into said chamber, and second means for detonating the explosivefluid in said elongated conduit to produce a high-velocity explosivefront therethrough and means for automatically removing liquidcondensate from said expansible chamber during the operating cyclethereof. 2. The apparatus of claim I wherein the lengthto-diameter ratioofthe elongated conduit is between 75 to l and 300 to l.

3. The apparatus of claim 1 wherein said first means further c m rises achamber housing for receiving said ex losive flui said elongated conduitbeing arranged to prev] e fluid communication between the interior ofsaid chamber housing and said expansible chamber, and wherein saidsecond means includes a spark ignition device extending into saidchamber housing for igniting explosive fluid therein.

4. The apparatus of claim 1 wherein the means for removing liquidcondensate from said expansible chamber comprises means for permittingliquid passage from the chamber and preventing liquid passage into thechamber.

5. The apparatus of claim 1 wherein said supporting structure includes aplurality of elongated, parallel, spaced-apart tubular members arrangedin a closed curvilinear path and bell-shaped means connected to one endof the tubular means to direct water into said tubular members andclosure means connecting together the tubular members at the end thereofopposite the bell-shaped members to prevent ingress of water into thespace defined by said tubular members and said inflatable member, saidclosure member comprising a plate between the tubular members and abell-shaped member connected to the plate and extending outwardly fromthe tubular members and away from the bell-shaped member, and whereinthe means for automatically removing liquid condensate includes aventuri pump within the bell-shaped member, hydraulically connected tothe interior of the enclosure, and a line extending through one of saidtubular members to said venturi pump for conducting a high-pressureliquid stream to said pump for actuating said pump and removing liquidfrom the interior of said enclosure.

6. In a seismic wave energy source for use while submerged in a liquidmedium comprising a support structure having a towing end and a trailingend, an expansible elastic member supported by and disposed upon atleast a portion of the supporting structure to define an expansiblechamber therewith. means for introducing an explosive fluid into thechamber and means for detonating the explosive fluid, the improvementcomprising pump means for removing liquid condensate from saidenclosure.

7. The apparatus of claim 6 wherein said means for removing liquidcondensate is a venturi pump, and wherein a line extends from said pumpto a remote location for conducting a high-pressure liquid stream tosaid pump for actuating said pump.

8. In a seismic wave energy source for use while submerged in a liquidmedium comprising a support structure having a towing end and a trailingend, an expansible elastic member supported by and disposed upon atleast a portion of the supporting structure to define an expansiblechamber therewith, means for introducing an explosive fluid into thechamber, and means for detonating the explosive fluid, the improvementcomprising:

means for automatically removing liquid condensate from said chamberduring the operating cycle of the energy source.

9. in a seismic wave energy source for use while submerged in a liquidmedium comprising a support structure, an expansible elastic membersupported by and disposed upon at least a portion of the supportingstructure to define an expansible chamber therewith, means forintroducing an explosive fluid into the chamber, and means fordetonating the explosive fluid, the improvement comprising:

means for automatically removing liquid condensate from said chamberduring the operating cycle of the energy source.

1. A seismic wave energy source for use while submerged in a liquidmedium comprising: a supporting structure, an expansible elastic membersupported by and disposed upon at least a portion of the supportingstructure to define an expansible chamber therewith, means fordischarging gases from said structure, first means comprising anelongated conduit extending into said supporting structure forintroducing explosive fluid through the conduit into said chamber, andsecond means for detonating the explosive fluid in said elongatedconduit to produce a high-velocity explosive front therethrough andmeans for automatically removing liquid condensate from said expansiblechamber during the operating cycle thereof.
 2. The apparatus of claim 1wherein the length-to-diameter ratio of the elongated conduit is between75 to 1 and 300 to
 1. 3. The apparatus of claim 1 wherein said firstmeans further comprises a chamber housing for receiving said explosivefluid, said elongated conduit being arranged to provide fluidcommunication between the interior of said chamber housing and saidexpansible chamber, and wherein said second means includes a sparkignition device extending into said chamber housing for ignitingexplosive fluid therein.
 4. The apparatus of claim 1 wherein the meansfor removing liquid condensate from said expansible chamber comprisesmeans for permitting liquid passage from the chamber and preventingliquid passage into the chamber.
 5. The apparatus of claim 1 whereinsaid supporting structure includes a plurality of elongated, parallel,spaced-apart tubular members arranged in a closed curvilinear path andbell-shaped means connected to one end of the tubular means to directwater into said tubular members and closure means connecting togetherthe tubular members at the end thereof opposite the bell-shaped membersto prevent ingress of water into the space defined by said tubularmembers and said inflatable member, said closure member comprising aplate between the tubular members and a bell-shaped member connected tothe plate and extending outwardly from the tubular members and away fromthe bell-shaped member, and wherein the means for automatically removingliquid condensate includes a venturi pump within the bell-shaped member,hydraulically connected to the interior of the enclosure, and a lineextending through one of said tubular members to said venturi pump forconducting a high-pressure liquid stream to said pump for actuating saidpump and removing liquid from the interior of said enclosure.
 6. In aseismic wave energy source for use while submerged in a liquid mediumcomprising a support structure having a towing end and a trailing end,an Expansible elastic member supported by and disposed upon at least aportion of the supporting structure to define an expansible chambertherewith, means for introducing an explosive fluid into the chamber andmeans for detonating the explosive fluid, the improvement comprisingpump means for removing liquid condensate from said enclosure.
 7. Theapparatus of claim 6 wherein said means for removing liquid condensateis a venturi pump, and wherein a line extends from said pump to a remotelocation for conducting a high-pressure liquid stream to said pump foractuating said pump.
 8. In a seismic wave energy source for use whilesubmerged in a liquid medium comprising a support structure having atowing end and a trailing end, an expansible elastic member supported byand disposed upon at least a portion of the supporting structure todefine an expansible chamber therewith, means for introducing anexplosive fluid into the chamber, and means for detonating the explosivefluid, the improvement comprising: means for automatically removingliquid condensate from said chamber during the operating cycle of theenergy source.
 9. In a seismic wave energy source for use whilesubmerged in a liquid medium comprising a support structure, anexpansible elastic member supported by and disposed upon at least aportion of the supporting structure to define an expansible chambertherewith, means for introducing an explosive fluid into the chamber,and means for detonating the explosive fluid, the improvementcomprising: means for automatically removing liquid condensate from saidchamber during the operating cycle of the energy source.